As is well known in the prior art most types of electric storage batteries generate combustible gases during their operation which gases are vented from the battery into the atmosphere. These gases can be ignited and cause explosions. Methods of controlling these explosions include placing materials such as fibers, plastics, glass materials in the space between the top of the electrolyte and the bottom of the battery cover to, allegedly, provide one or more advantages in the controlling of explosions. However, little is known in the prior art of providing any means for controlling the evaporation of water from the battery.
For example, in the prior art, Heinz Fritz et al. U.S. Pat. No. 4,076,901, the battery which operates at an elevated temperature, includes a vaporization-resistent layer over the electrolyte consisting of floating solid particles or a liquid, specifically referred to as paraffin oil.
H. E. Jensen described in his 1944 U.S. Pat. No. 2,341,382 the use of a material loosely disposed within the upper portion of the battery, which was held above the battery electrolyte level and thereby displaced the volume of gases within that area. No mention was made of controlling water loss.
More recently, patents such as that to Binder et al. U.S. Pat. No. 4,751,154, showed the use of a porous, compressible plastic material to attenuate the explosion of combustible gases accumulating in the battery. This material was described as having a unique bimodal pore distribution including a major portion of small pores effective for attenuation and a minor portion of large pores effective in gas and electrolyte management. The patent emphasizes that both open cell and fibrous materials may be utilized for these purposes. Once again, there is no mention of controlling the amount of water loss in the battery.
This latter patent also describes the materials as having reticulated or non-reticulated structures; defining non-reticulated as "not all of the cells are fully open although the material is permeable" and reticulated as "the cell membranes or bubbles are completely broken or open, resulting in higher permeability."
In spite of this prior art, little is known of methods for reducing water loss in batteries used in hot climates. For example, while the use of oil has proved effective, explosion testing of batteries has proved that flammable oil contributed to that hazard. Similarly, dense particles tend to contribute to the hazard of explosion.
Water loss in a battery can become extremely severe in hot climates, especially in locations where relative humidity is also low. The situation is worsened by the increasingly cramped space allowed under the hood of cars as the automotive designs become more aerodynamic. Underhood temperatures as high as 200.degree. F. have been measured and battery temperatures up to 180.degree. F. Thus a battery design which would reduce water loss would be beneficial especially in hot climates. Without proper maintenance, such as water additions, the specific gravity of the sulfuric acid electrolyte rises steadily, causing decreased battery life. If no water is added during its life, the battery may fail due to water loss.
Accordingly, it is an object of this invention to provide a method and material means for dramatically reducing water loss without increasing the likelihood of explosion. This and other objects of the invention will become apparent from the following description.
While we have discovered a material to aid in reducing the battery water loss, we have also developed an apparatus for inserting that material into that battery during assembly. Although the material and method are not known in the prior art, there is art on vacuum guns to accumulate small particulate matter and discharge it such as guns used in the pharmaceutical industry as, for example, those produced by Kinematics and Controls Corp. of Deerpark, N.Y.